Ortho-carboxyamidothioglycolic acid



Patented May 7, 1929.

UNITED STATES PATENT OFFICE. 4

NORBERT STEIGER, OF FRANKFORT-ON-THE-MAIN, AND ERWIN HOFFA ANT) HANS .HEYNA, OF HOCHST-ON-THE-MAIN, GERMANY, ASSIGNORS TO GRASSELLI DYE- STUFF CORPORATION, OF NEW YORK, N. Y., A. CORPORATION OF DELAWARE.

OBTHO-CARBOXYAMIDOTHIOGLYCOLIC ACID.

No Drawing. Application filed March 30, 1928, Serial No. 266,112, and in Germany March 31, 1927.

Our copending application Serial No. 266,110, filed on the same date, relates to new ortho-carboxyamidoarylthioglycolic-acids of the general formula:

/GONH: 1 sorncoon 2 wherein aryl means'a substituted aryl residue, and a process of making same which comprises reducing the corresponding ortho-cyanarylsulfochlorides under such conditions, whereby ortho-carboxyamidoarylmercaptans are formed, and condensing the products thus obtained in an alkaline solution with monochloroacctic-acid.

Our present invention relates to a certain embodiment of the above mentioned series of compounds of which the following is an illustrative example in which the parts are by weight andall temperatures are in centigrade degrees:

E wample:

35 parts of l-cyan-4-chlorobenzene-2-sulfochloride of the formula:

obtainable for instance according to the process mentioned in the copending application by starting from the corresponding para-chloroaniline-sulfonic-acid are dissolved in about 100 parts of benzene or chlorobenzene, and at ordinary temperature slowly 20 parts of zincdust are added, the temperature increasing to about After stirring for about an hour at this temperature the mass is'cooled down and at about 35 100 parts of hydrochloric-acid (al=1,19) and again 20 parts of zinc-dust are slowly added. The mass is stirred at ordinary temperature for some hours. The rr action is finished when a test shows that the well known mercapt-an reaction (namely a yellow coloration with lead acetate) does not increase any more. Care should be taken, that during the whole process of reduction practically no nitrogen of the cyanic-group is split of in form of ammonia. This can be ascertained in the following manner: A test of the reduction-mass is taken with time to time and is diluted with water,

the organic residue is filtered off, the filtrate is made alkaline and boiled. Only traces of ztiemmonia should be ascertainable in these sts.

When the reduction is finished the benzene or chloro-benzene respectively is distilled off and the residue is diluted with water and filtered off. The mcrcapto compound thus formed of the probable constitution of a 4 chlorobenzene 1 carboxyamidobenzene 2- mercaptan can directly be used for further technical purposes. It is without being purified mixed with about 300 parts of water and dissolved by addition of about 40 parts of a caustic soda solution of 33 B. and 10 parts of monochloroacetic-acid are added. The condensation takes place at ordinary temperatures and is finished in a relatively short time. For precipitating the free acid the mass is acidified preferably with addition of the same volume of a common salt solution.

The 4 chloro 1 carboxyamidobenzene 2 thioglycolic acid of the formula:

ONE:

Cl SCHgCOOH thus separates as a white crystalline powder. It is soluble in hot water and in the usual organic solvents, crystallizing therefrom as colorless needles, melting in a pure state at about We claim:

As a new compound the 4-chloro-1-carboxyamido-benzene-2-thioglycolic acid of the formula com!

.01 sci-1100011,

being when dry a white crystalline powder NORBERT STEIGER. .ERWIN HOFFA. HANS HEYNA. 

